Structural and Thermal Behaviour of Insulated FRP-Strengthened Reinforced Concrete Beams and Slabs in Fire
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Despite the superior properties of Fibre Reinforced Polymer (FRP) materials, the use of FRPs in buildings is limited. A key cause of concern for their use in buildings arises from their poor performance in fire occurrences. This thesis presents the results of fire performance of Reinforced Concrete (RC) beams and slabs strengthened with externally bonded FRP sheets. The performance and effectiveness of insulation materials and techniques are also investigated in this thesis. Two full-scale reinforced concrete T-beams and two intermediate-scale slabs were strengthened in flexure with carbon and glass fibre reinforced polymer sheets and insulated with a layer of spray-on material. The T-beams and slabs were then exposed to a standard fire. Fire test results show that fire endurances of more than 4 h can be achieved using an appropriate insulation system. Tests were performed in order to understand the behaviour of FRP concrete bond at high temperatures. An empirical model was then formulated to describe the bond strength deterioration due to temperature rise. Innovative measurement techniques were employed throughout the experiments to measure important observables like strain and temperature. Meanwhile, the effectiveness and practicality of techniques such as Fibre Optic Sensing (FOS) and Particle Image Velocimetry (PIV) for high temperature applications were investigated. A numerical finite-volume heat transfer model was developed to simulate the heat transfer phenomenon. The validity of the numerical model was verified by comparing the results with the results from the fire tests. By using this model, parametric analyses were performed to investigate the effect of different fire scenarios on the performance of the insulated beams. To simulate the structural performance of the T-beams a numerical model which was capable of predicting stresses and strains and deflections of a heated beam was developed. The model is capable of incorporating the effects of axial forces in the response of a restrained beam. This model was verified and used in combination with the thermal model to simulate the deflections of T-beams in fire.